Add link to enum type. Put the signal number -> Signal section on its own paragraph to keep it from getting lost in the preceding text

Author: samcv

doc/Type/Supply.pod6

@@ -599,12 +599,16 @@ the supply.  For example:
 
     signal(SIGINT).tap( { say "Thank you for your attention"; exit 0 } );
 
-would catch Control-C, thank you, and then exit.  The list of supported
-signals can be found by checking Signal::.keys (as you would any enum).
-To go from a signal number to Signal, you can do something like this:
+would catch Control-C, thank you, and then exit.
+
+To go from a signal number to a Signal, you can do something like this:
 
     signal(Signal(2)).tap( -> $sig { say "Received signal: $sig" } );
 
+The list of supported signals can be found by checking Signal::.keys (as
+you would any enum). For more details on how enums work see
+L<enum|/language/typesystem#enum>.
+
 =head2 method IO::Notification.watch-path
 
 =for code :skip-test